Singapore's economy ranked third in the survey. Emerging economies China, Brazil, and India all showed improvement, while Russia's ranking fell.

In other economic news, a government report said Tuesday that U.S. consumer borrowing slid by $21.6 billion in July - the sixth month in a row that borrowing declined. That contributes to less spending in the consumer-driven U.S. economy.

Meanwhile, 15 major banks from the U.S. and Europe sent a letter to the U.S. Federal Reserve Tuesday, promising to be more transparent when dealing with complex investments known as derivatives. Some critics say loose regulation of the trading of derivatives played a big role in the economic crisis that began one year ago.

The banks say they will use a central forum to make some transactions, to make it easier to monitor them.

Derivatives are financial instruments whose value is based on something else, like home loans or crude oil.